payback

I installed my solar hot water system about six years ago. It’s a good system. I have two 4’x8’ AE-32 flat-plate collectors (manufactured by Alternate Energy Technologies), a Superstor Ultra stainless-steel tank (at 80 gallons, it’s a little small, but it’s what I could afford), and an El Sid DC pump from Ivan Labs. Since I installed the equipment myself, it cost significantly less than a professionally installed system.

Until now, Patrick McCombe has believed that improvements to the envelope of his home should come before an investment in photovoltaic panels. Now he's weighing a deal that seems too good to pass up.
McCombe lives in Connecticut (he's an associate editor at Fine Homebuilding magazine) and he recently attended an informational meeting sponsored by an organization working to lower the cost of PV. Panels could be purchased or leased, but the bottom line was that with federal and state incentives, McCombe could buy a 10-kilowatt array for $15,000.

This Q&A Spotlight starts with a simple question from Anders Lewendal, a builder in Bozeman, Montana. If building to the Passivhaus standard is so cost-effective, Lewendal wants to know, why are only a handful of these houses getting built in the U.S. every year?
"Either the cost of fuel is too low or the cost of a Passive House is too high," Lewendal writes in a post at Green Building Advisor's Q&A forum.

Anders Lewendal, a builder in Bozeman, Montana, is wrestling with a familiar dilemma: What's the right amount of insulation to put in a house?
"Our theory," he writes in Q&A post at GreenBuildingAdvisor, "is that too little insulation wastes energy and equally, too much insulation wastes energy. Where is the sweet spot in each climate zone?"
To that end, Lewendal is proposing more performance testing.

There’s an age-old question of how much insulation to install in our homes. Conventional wisdom says to add more until the “payback” for the added insulation isn’t worth it — until the energy savings that will result from the insulation doesn’t pay back the cost of that insulation quickly enough.
Energy and environmental consultant Andy Shapiro, of Energy Balance, Inc. in Montpelier, suggests a different approach: basing that decision on the cost of a solar electric system.

A common Passivhaus topic that rears its head every now and again is the embodied energy of construction. While this can be an important issue, we generally feel it’s a moot point for Passivhaus projects – especially the ones we design (owing to better optimized assemblies and less insulation!).

If you are considering investing in an energy-efficiency improvement for your home — for example, additional attic insulation or a photovoltaic system — you probably expect the investment will lower your energy bills. So it’s only natural to ask, “Is this a good investment?”
For example, let’s say that you are considering spending $5,000 on an improvement that will save you $350 a year on your energy bills. Does the investment make economic sense? The answer, of course, is “it depends.”

If we let simple or even net-value payback analysis alone drive the economics of high-performance buildings, we might as well throw in the towel. It is truly crazy to apply just this approach to long-lived durable goods, such as homes.